1. Field of the Invention
The invention relates to a novel gin stand for ginning seed cotton or reginning cotton seed.
2. Description of the Prior Art
The removal of seeds, trash or foreign matter from cotton lint presents significant problems to cotton producers and textile mills. High levels of such impurities reduce the price the producer receives for the product. However, efforts to remove seeds and reduce trash levels often cause fiber damage, decreasing the quality of the resulting yarn and cloth.
In harvesting, seed cotton is stripped or picked from the plant, deposited in a trailer or other vehicle, and transported to a cotton gin. The cotton gin has apparatus for receiving the seed cotton, removing the seeds from the long cotton fiber or lint, cleaning the lint, and pressing the lint into bales for transport to textile mills or compresses for further operation. Lint-free seed recovered from the ginning operation may also be retained for the production of oil, as a protein supplement in animal feed, and for planting.
In a typical ginning process, seed cotton is transported from a trailer or module into a green-boll trap in the gin where green-bolls, rocks and other heavy foreign matter are removed to prevent damage to the machinery. The cotton is then automatically transported into a series of dryers followed by a stick machine where the cotton is dried to desired moisture levels and large pieces of trash are removed. After drying and cleaning, the cotton is distributed to each saw type gin stand (referred to herein as a gin saw stand) by a conveyer whereupon it is metered into the gin saw stands with an extractor-feeder. From the gin stand, the cotton fiber is next formed into a batt and transported to lint cleaners for further cleaning before baling.
A commercial saw type gin stand which is currently in use is shown in FIG. 1. Referring to the figure, conventional gin saw stands 10 typically contain a large chamber referred to as a huller front 11 wherein the seed cotton is deposited. A gin saw cylinder 12, composed of a large number of spaced apart circular blades 13 rotating about a common axis 14, is combined with operably associated ribs positioned between the blades of the saws in order to strip the lint from the seed. Briefly, cotton in the huller front 11 is grasped by the teeth on the outer periphery of a first gin saw cylinder 12 and drawn through a first set of widely spaced ribs known as huller ribs 20 positioned between the saw blades. Delivery of the cotton into contact with the teeth of the first saw is assisted by a rotating toothed cylinder, referred to as the picker roller 21, which pushes the cotton in the huller front against the saw. This picker roller is generally positioned with its axis 22 approximately lateral to the axis 14 of the first saw 12, with its outer periphery spaced apart from the outer periphery or teeth of the saw. The locks of cotton are drawn upwardly through the huller ribs and into the lower portion of a roll or seed-roll box 25 positioned above the axis of the saw where the seeds with attached cotton accumulate in a large mass. This mass of seeds and/or seed cotton is commonly referred to as the roll.
The actual separation of the seed from lint takes place in the roll box 25 of the gin stand. A second set of ribs, referred to as the ginning ribs 26, are located in the spaces between the blades of the saw at the downstream end of the roll box, and extend from a position above the periphery of the saw downward through the spaces to near or below the bottom of the saw. Cotton fibers in the roll box are again caught by the teeth of the first saw and passed toward the ginning ribs 26. As the teeth of the saw pass between the ginning ribs, they pull the lint from the seeds, which are too large to pass between adjacent ribs. The seed-free lint proceeds past the ginning ribs 26 where it is removed by a doffing brush 27 and passed out of the gin stand. Meanwhile, seeds which have all or a portion of their lint or long fibers removed therefrom pass downward along the ginning ribs between the saw blades where they eventually fall onto a conveyor 28 positioned below the first saw. In contrast to the lint-free seeds, seeds which retain long fibers thereon are generally pushed back into the mass of seed/cotton in the roll box 25, awaiting to be caught by the saw and repeat the ginning operation. In some models of gin saws, agitators having a serrated outer edge have been placed in the roll box (on an angle relative to the first saw) to assist the first saw in turning the roll of material within the roll box.
A thorough description of a variety commercially available gin saw stands and their operation is provided by Anthony and Mayfield (ed.), Cotton Ginner's Handbook, Agricultural Handbook No. 503, United States Department of Agriculture, Agricultural Research Service, Washington, D.C., 1994, the contents of which are is incorporated in their entirety by reference herein.
Throughput through these existing gin saw stands is reduced, primarily because the removal of the cleaned seeds is impaired by the upward passage of new seed cotton being fed in through the huller front, and because the pickup of lint from the mass in the roll box is slowed by the inability of the saws to pick up seeds having relatively few attached fibers and thereby turn the mass to expose fresh seed cotton. Furthermore, the level of lint removal from the seeds cannot be readily controlled, and seeds discarded from conventional gin stands may contain relatively high levels of lint remaining thereon.
Gin stand performance is also related to the seed roll density. A loose roll assures minimum fiber damage, while a roll that is too tight may result in fiber and seed damage. The gin stand needs to be operated at the highest roll density compatible with low fiber damage to achieve maximum processing capacity. Conventional gin stand feeder controls usually sense the load on the gin saw motor for the control criterion. Adjustment of the position of the seed fingers extending into the roll box may also provide a small variation in the cleaning level for a given motor load. Other gin stand controls sense the pressure within the roll box as the control criterion. These systems prevent the operator from maintaining the cleaning at a fixed level independent of processing rate, and cleaning suffers as processing rate increases. This has lead to the development of gin stands having more saws and of increased width in an attempt to increase processing rate. However, with these systems processing at the levels required in modern cotton gins, about 3-5% of the lint may be left unginned on the seeds.